Effect of FSW Parameters on The Microstructure and Mechanical Properties of T-joints between Dissimilar Al-Alloys

The main purpose of this research is to develop T-joints between the aluminum AA 2024-T4 and AA 7075-T6 using friction stir welding.  The effect of tool geometries, tool traveling speed, and rotational rate in the welded T-joints were investigated and discussed. Three different tools were used with different shoulder to pin ratios 3.28, 3.36, and 4.31. After optimization, the best tool dimension has used with the different rotational and welding speeds. Three tool traverse speeds of 50, 75, and 100 mm/min were used. Two rotation rates of 800 rpm and 1000 rpm were applied. After FSW, at a number of the above FSW parameters' combinations, macrostructure and microstructure analyses were done using optical microscopy. In order to have an insight into the mechanical properties, hardness measurements and tensile testing were carried out. Using small shoulder to pin ratio produced visually unacceptable T-joint. Opposite happened by using the tool with 4.31 of shoulder to pin ratio. Furthermore, the results showed sound T-welds with no obvious defects at high rotational rate of 1000 rpm with the two used traveling speeds. Asymmetric temperature distribution was observed between the two sides, advance side (AS) and retreating side (RS

Poverty, protests and pandemics: what can we learn from community resilience?

The destruction of property, theft and violence that occurred in South Africa, particularly in KZN and Gauteng in the week of 12 July 2021 had a significant impact on the national psyche. As we try to come to terms with the magnitude of the consequences on the political, economic, psychological and social levels, what are the lessons that we can draw from this adversity? This commentary draws on the notion of community resilience to understand what has happened, and how it may provide markers for the future. The commentary begins with a short overview of the notion of community resilience, followed by a discussion of its utility to explain the events as well as lessons for the future

In vitro technique for selecting onion FOR white rot disease- resistance

In vitro selection is one of the most effective and efficient techniques for plant improvement. This is due to its ability to isolate plants with the desired character(s), either by applying a selection agent on the culture media to drive the selection of somaclones with the required character(s), or by establishing particular conditions that change in the genomes of somaclones toward the required character. The objective of this study was to identify a suitable protocol for in vitro selection of Allium white rot disease ( Sclerotium cepivorum ) tolerance in commercial Egyptian onion varieties, namely Giza 20, Giza 6 and Beheri Red. Oxalic acid (OA), the phytotoxin produced by Sclerotium cepivorum, was used as the selective agent. Seeds of the three Egyptian varieties were germinated on four concentrations (0.0, 0.02, 0.2, 2 and 20 mM) of Oxalic acid. Among the tested cultivars, Beheri Red had the highest germination frequency (52%) at all concentrations tested, followed by Giza 20 (42.6%), and Giza 6 at (32%). Cotyledon explants from the varieties were cultured on toxic MSBDK> medium, supplemented with 0, 3, 6 and 12 mM OA. The survival of calli on MSBDK free toxic medium was 70.7% for all tested cultivars; however, MSBDK-stressed medium, with 3 mM OA reduced the viable calli to 42.1%. The highest OA concentration (12 mM) completely inhibited calli induction from cotyledons explants. A medium supplement with 3 mM OA retarded 80% of calli growth. Among 156 tested calli of Beheri Red, only 23 calli (14.7%) survived on toxic medium for 45 days. Similarly, there was 15.6% survival for Giza 20 calli, while 40.1% of the Giza 6 calli survived. Plantlets were regenerated from surviving calli and transplanted onto ex vitro, and formed bulb after acclimatisation.La selection In vitro est l\u2019une des techniques les plus efficaces en amelioration des plantes. Ceci est d\ufb \ue1 la capacit\ue9 qu\u2019\ue1 cette technique de permettre l\u2019isolation des plants avec des caract\ue8res d\ue9sir\ue9s. Ceci se fait de deux mani\ue8res; soit en appliquant un agent de selection sur le milieu de culture afin d\u2019orienter la s\ue9lection somaclonale de fa\ue7on \ue1 pr\ue9server le caract\ue8re desir\ue9, ou, en cr\ue9ant des conditions particuli\ue8res visant \ue1 modifier le genome afin dans le sens des caract\ue8res voulus. L\u2019ojectif de l\u2019\ue9tude \ue9tait d\u2019identifier un protocole ad\ue9quat pour la selection in vitro de la tol\ue9rance \ue1 la maladie de pourriture blanche ( Sclerotium cepivorum ) chez les vari\ue9t\ue9s commerciales d\u2019oignon en Egypte, en loccurence, Giza 20, Giza 6 et Beheri Red. L\u2019acide oxalique (OA), la phytotoxine produite par Sclerotium cepivorum, ont \ue9t\ue9 utilis\ue9s comme agent de s\ue9lection. Les semences des trois vari\ue9t\ue9s Egyptienne d\u2019oignon ont \ue9t\ue9 cultiv\ue9es sur quatre milieu de culture de diff\ue9rentes concentrations d\u2019acide oxalique (0.0, 0.02, 0.2, 2 et 20 mM). parmi les cultivars test\ue9s, Beheri Red avait la fr\ue9quence de germination la plus (52%) sur tous les quatre milieu de culture, puis vint Giza 20 (42,6%) et Giza 6 (32%). Des explants de cotyledons ont \ue9t\ue9 cultiv\ue9s sur milieu toxique MSBDK, additionn\ue9 de 0, 3, 6 et 12 mM de OA. Les calls survivants sur milieu toxique mais ne contenant pas de MSBDK \ue9tait de 70.7% pour tous les cultivars test\ue9s; n\ue9anmoins, le milieu contenant MSBDK, avec 3 mM de OA a caus\ue9 la r\ue9duction des calls viables de 42.1%. la plus forte concentration de OA (12 mM) a caus\ue9 une inhibiton complete de la r\ue9g\ue9ration des calls \ue1 partir des explants de cotyledons. Un milieu additionn\ue9 de 3 mM de OA \ue1 retard\ue9 la croissance des calls de 80%. Parmi les 156 calls de Beheri Red test\ue9s, seuls 23 calls, soit 14,7%, ont surv\ue9cu sur milieu toxique pendant 45 jours. De m\ueame, il y avait 15,6% de calls survivants Giza 20 calli, tandis que 40,1% des calls de Giza 6 ont surv\ue9cu. Des plantules ont \ue9t\ue9 r\ue9g\ue9n\ue9r\ue9 \ue1 partir des calls survivants et ceux ci ont \ue9t\ue9 transplant\ue9 sur milieu naturel, ils forment des bulbes d\u2019oignons apr\ue8s un temps d\u2019acclimatation

Ecological Distribution of Virulent Multidrug-Resistant Staphylococcus aureus in Livestock, Environment, and Dairy Products

Staphylococcus aureus is one of the most common causes of mastitis, leading to severe economic losses in the dairy industry. It is also zoonotic, with potential risks to public health. This study aimed to detect the occurrence of S. aureus-resistant strains isolated from cattle, buffalo, their environment, milk and dairy products; and to investigate the extent of animal, ecological, and food contamination by methicillin-resistant (MRSA) or enterotoxigenic S. aureus. Samples (n = 350) were collected from four animal (two cattle and two buffalo) farms, i.e., their environment. Thirty Karish cheese samples were collected from 10 markets in Mansoura, Egypt. S. aureus was detected in 17.9%, 17.6%, and 16.7% of samples collected from cattle, buffalo and Karish cheese, respectively. About 19% of isolated S. aureus strains carried the mecA gene. The distribution of the mecA gene was high in isolates from Karish cheese (60%), followed by samples collected from buffalo (16.2%) and cattle (16%). More than 34% of isolated S. aureus strains were enterotoxigenic, and the presence of enterotoxin genes was higher in isolates from Karish cheese (80%) than those from cattle (48%) and buffalo (18.9%). The most predominant enterotoxin gene among isolated S. aureus strains was the sea gene (26.9%), followed by sec (4.5%) and sed (3%) genes. Isolated strains were resistant to clindamycin (100%), kanamycin (97%), nalidixic acid (86.6%), cefotaxime (73.1%) sulphamethazole—trimethoprim (65.6%). Meanwhile, 95.5%, 94%, 86.6% and 77.7% of S. aureus strains were sensitive to ciprofloxacin, amikacin, imipenem and both cefoxitin and gentamycin, respectively. In conclusion, the presence of enterotoxigenic- and methicillin-resistant S. aureus strains in animals, their environment, and dairy products represents a public health concern, particularly in small-scale dairy farms in Egypt. To reduce the risk of infection of livestock and humans with resistant strains, strict regulations and guidelines for antimicrobial use in such a system are urgently required

Perspective Chapter: The Toxic Silver (Hg)

In the late 1950s, residents of a Japanese fishing village known as “Minamata” began falling ill and dying at an alarming rate. The Japanese authorities stated that methyl-mercury-rich seafood and shellfish caused the sickness. Burning fossil fuels represent ≈52.7% of Hg emissions. The majorities of mercury’s compounds are volatile and thus travel hundreds of miles with wind before being deposited on the earth’s surface. High acidity and dissolved organic carbon increase Hg-mobility in soil to enter the food chain. Additionally, Hg is taken up by areal plant parts via gas exchange. Mercury has no identified role in plants while exhibiting high affinity to form complexes with soft ligands such as sulfur and this consequently inactivates amino acids and sulfur-containing antioxidants. Long-term human exposure to Hg leads to neurotoxicity in children and adults, immunological, cardiac, and motor reproductive and genetic disorders. Accordingly, remediating contaminated soils has become an obligation. Mercury, like other potentially toxic elements, is not biodegradable, and therefore, its remediation should encompass either removal of Hg from soils or even its immobilization. This chapter discusses Hg’s chemical behavior, sources, health dangers, and soil remediation methods to lower Hg levels